Automatic stop and restart device for an engine

ABSTRACT

Provided is an automatic stop and restart device for an engine that is capable of suppressing occurrence of an abnormal condition even if a transmission state is changed during an engine restart process after an engine restart condition is satisfied in an automatic engine stop process. A controller performs the automatic engine stop process and the engine restart process. If a determined state of a transmission is a drive range, a transmission state determination unit drives a pinion gear thrust unit at timing determined by a first pinion gear thrust timing determination unit. If the determined state of the transmission is a non-drive range, the transmission state determination unit drives the pinion gear thrust unit at timing determined by a second pinion gear thrust timing determination unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 12/957,956filed Dec. 1, 2010, which is the disclosure of which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an automatic stop and restart devicefor an engine, which stops an engine automatically when a predeterminedautomatic engine stop condition is satisfied and restarts the enginewhen a predetermined restart condition is satisfied after the automaticengine stop condition is satisfied.

2. Description of the Related Art

In recent years, there are developed automatic engine stop and restartsystems which stop an engine automatically and then restart the engineautomatically for a purpose of improving fuel efficiency of automobilesor decreasing environmental load. The automatic engine stop and restartsystem automatically stops the engine if a predetermined automaticengine stop condition for stopping the engine is satisfied by a driver'soperation (e.g., if a brake operation is performed at vehicle speedunder a predetermined speed). In addition, the automatic engine stop andrestart system automatically restarts the engine if a predeterminedrestart condition is satisfied by a driver's operation (e.g., if a brakereleasing operation or a gas pedal depressing operation is performed).

For instance, Japanese Patent No. 4214401 discloses a conventionaldevice in which, if a request for restart is issued during a period ofdecreasing engine rotation just after idle stop, a controller starts acranking operation without waiting for the engine rotation beingcompletely stopped. More specifically, in this conventional device, if arequest for restart is issued during a period of decreasing enginerotation just after idle stop, the controller controls a starter piniongear to rotate. Further, when the rotation speed of the starter piniongear is synchronized with a predicted rotation speed of a ring gear, thecontroller controls the starter pinion gear to engage with the ring gearso as to start the cranking operation.

Next, operation timings of the conventional device as disclosed inJapanese Patent No. 4214401 are described with reference to a timingchart illustrated in FIG. 31. In FIG. 31, a ring gear rotation speed isrepresented by reference numeral 1001; a pinion gear rotation speed,1002; a starter drive signal, 1003; and a pinion gear thrust signal,1004. An automatic engine stop condition is satisfied at time t1, andthe controller starts the engine stop process. After that, an enginerestart condition is satisfied at time t2, and the controller turns onthe starter drive signal so that the pinion gear starts to rotate.

Further, at time t3, it is predicted that the ring gear rotation speedand the pinion gear rotation speed are synchronized with each otherafter a pinion gear abutment delay time ΔT. Therefore, the controllerturns on the pinion gear thrust signal. At time t4, the ring gearrotation speed and the pinion gear rotation speed are synchronized witheach other. At the same time, the pinion gear abuts against and engageswith the ring gear. After that, the controller controls the pinion gearto rotate and drives the ring gear so that the engine is cranked and isrestarted.

In the conventional device as disclosed in Japanese Patent No. 4214401,the controller predicts the ring gear rotation speed in the future andcontrols timing to thrust the pinion gear in synchronization with thetiming when it is predicted that the pinion gear rotation speed and thering gear rotation speed are synchronized with each other. However, theconventional device as disclosed in Japanese Patent No. 4214401considers nothing about the case where the driver selects the non-driverange during the engine restart process.

Therefore, in this case, a ring gear rotation speed decrease amount inthe non-drive range is different from a ring gear rotation speeddecrease amount in the drive range. Therefore, the pinion gear rotationspeed and the ring gear rotation speed cannot be synchronized at a timepoint of abutment, and the pinion gear is pressed to the ring gear inthe state where the gears cannot engage with each other. As a result, inthe conventional device as disclosed in Japanese Patent No. 4214401,there is a risk that noise is generated or a mechanism is broken.

The above-mentioned problem of the conventional device as disclosed inJapanese Patent No. 4214401 is described with reference to a timingchart illustrated in FIG. 32. In FIG. 32, the ring gear rotation speedis represented by reference numeral 1001; the pinion gear rotationspeed, 1002; the starter drive signal, 1003; the pinion gear thrustsignal, 1004; and a transmission state, 1005. At a time point t1, theautomatic engine stop condition is satisfied, and the controller startsthe engine stop process.

After that, at a time point t2, the engine restart condition issatisfied. Therefore, the controller turns on the starter drive signalso as to control the pinion gear to start rotating. Then, at a timepoint t3, the controller predicts that the ring gear rotation speed andthe pinion gear rotation speed are synchronized with each other afterthe pinion gear abutment delay time ΔT and turns on the pinion gearthrust signal.

At a time point t4, the transmission state is changed from a D range toan N range, and hence the ring gear rotation speed decrease amountchanges. As a result, at a time point t5, the ring gear and the piniongear abut against each other but cannot engage with each other becausethe ring gear rotation speed and the pinion gear rotation speed are notsynchronized with each other. Therefore, noise may be generated or themechanism may be broken.

SUMMARY OF THE INVENTION

The present invention has been made for solving the above-mentionedproblem, and an object thereof is to provide an automatic stop andrestart device for an engine that is capable of suppressing occurrenceof an abnormal condition such as noise or a breakdown even if an enginerestart condition is satisfied in an automatic engine stop process and atransmission state is changed during an engine restart processthereafter.

According to the present invention, there is provided an automatic stopand restart device for an engine that is disposed in a start andtransmission system of a vehicle which includes: a transmission forchanging gears to transmit power of the engine to driving wheels of thevehicle; a transmission operation device for receiving an externaltransmission operation to operate a transmission state of thetransmission; a ring gear that is provided to a crank shaft of theengine, a starter motor for starting the engine; a pinion gear that iscapable of approaching and separating from the ring gear and is drivenby the starter motor to rotate; pinion gear thrust means for thrustingthe pinion gear to the ring gear so that the pinion gear engages withthe ring gear to crank the engine; and ring gear rotation speeddetection means for detecting a ring gear rotation speed, the automaticstop and restart device including a controller which includestransmission state determination means for determining whether thetransmission is in a drive range or in a non-drive range, the controllerperforming an automatic stop process for the engine if a predeterminedautomatic engine stop condition is satisfied, and a restart process forthe engine by controlling drive of the starter motor and the pinion gearthrust means if a predetermined restart condition is satisfied after thepredetermined automatic engine stop condition is satisfied, in which thecontroller further includes: starter drive time measurement means formeasuring starter motor drive time from a time point when the drive ofthe starter motor is started; pinion gear rotation speed estimationmeans for estimating a pinion gear rotation speed based on the startermotor drive time; first pinion gear thrust timing determination meansfor driving the pinion gear thrust means at timing when a differencebetween the ring gear rotation speed and the pinion gear rotation speedin a case where the transmission is in the drive range becomes a firstpredetermined value corresponding to a speed decrease amount of the ringgear rotation speed in the case where the transmission is in the driverange; and second pinion gear thrust timing determination means fordriving the pinion gear thrust means at timing when a difference betweenthe ring gear rotation speed and the pinion gear rotation speed in acase where the transmission is in the non-drive range becomes a secondpredetermined value corresponding to a speed decrease amount of the ringgear rotation speed in the case where the transmission is in thenon-drive range.

According to the automatic stop and restart device for an engine of thepresent invention, the controller includes the first pinion gear thrusttiming determination means for driving the pinion gear thrust means atthe timing when the difference between the ring gear rotation speed andthe pinion gear rotation speed in the case where the transmission is inthe drive range becomes the first predetermined value corresponding tothe speed decrease amount of the ring gear rotation speed in the casewhere the transmission is in the drive range, and the second pinion gearthrust timing determination means for driving the pinion gear thrustmeans at the timing when the difference between the ring gear rotationspeed and the pinion gear rotation speed in the case where thetransmission is in the non-drive range becomes the second predeterminedvalue corresponding to the speed decrease amount of the ring gearrotation speed in the case where the transmission is in the non-driverange. Therefore, the pinion gear does not abut against the ring gear inthe state where the ring gear rotation speed and the pinion gearrotation speed are not synchronized with each other. Thus, even if theengine restart condition is satisfied during the automatic engine stopprocess and the transmission state is changed during the engine restartprocess thereafter, occurrence of an abnormal condition such as noise ora breakdown can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a configuration diagram illustrating an automatic stop andrestart device for an engine according to Embodiment 1 of the presentinvention;

FIG. 2 is a configuration diagram illustrating a starter illustrated inFIG. 1;

FIG. 3 is a block diagram illustrating a controller illustrated in FIG.1;

FIG. 4 is a timing chart illustrating operation timings of an automaticengine stop and restart process by the controller illustrated in FIG. 1;

FIG. 5 is a graph illustrating a map for estimating a pinion gearrotation speed;

FIG. 6 is a graph illustrating a map for determining a pinion gearthrust timing;

FIG. 7 is a flowchart illustrating an operation of the controllerillustrated in FIG. 1;

FIG. 8 is a flowchart illustrating an operation of the controllerillustrated in FIG. 1;

FIG. 9 is a flowchart illustrating an operation of the controllerillustrated in FIG. 1;

FIG. 10 is a flowchart illustrating an operation of the controllerillustrated in FIG. 1;

FIG. 11 is a flowchart illustrating an operation of the controllerillustrated in FIG. 1;

FIG. 12 is a timing chart illustrating operation timings of an automaticengine stop and restart process by a controller according to Embodiment2 of the present invention;

FIG. 13 is a flowchart illustrating an operation of the controlleraccording to Embodiment 2 of the present invention;

FIG. 14 is a flowchart illustrating an operation of the controlleraccording to Embodiment 2 of the present invention;

FIG. 15 is a flowchart illustrating an operation of the controlleraccording to Embodiment 2 of the present invention;

FIG. 16 is a timing chart illustrating operation timings of an automaticengine stop and restart process by a controller according to Embodiment3 of the present invention;

FIG. 17 is a flowchart illustrating an operation of the controlleraccording to Embodiment 3 of the present invention;

FIG. 18 is a flowchart illustrating an operation of the controlleraccording to Embodiment 3 of the present invention;

FIG. 19 is a timing chart illustrating operation timings of an automaticengine stop and restart process by a controller according to Embodiment4 of the present invention;

FIG. 20 is a flowchart illustrating an operation of the controlleraccording to Embodiment 4 of the present invention;

FIG. 21 is a flowchart illustrating an operation of the controlleraccording to Embodiment 4 of the present invention;

FIG. 22 is a flowchart illustrating an operation of the controlleraccording to Embodiment 4 of the present invention;

FIG. 23 is a graph illustrating a map for estimating a pinion gearrotation speed;

FIG. 24 is a graph illustrating a map for predicting a gear rotationstop time point;

FIG. 25 is a timing chart illustrating operation timings of an automaticengine stop and restart process by a controller according to Embodiment5 of the present invention;

FIG. 26 is a timing chart illustrating operation timings of an automaticengine stop and restart process by a controller according to Embodiment6 of the present invention;

FIG. 27 is a flowchart illustrating an operation of the controlleraccording to Embodiment 6 of the present invention;

FIG. 28 is a flowchart illustrating an operation of the controlleraccording to Embodiment 6 of the present invention;

FIG. 29 is a flowchart illustrating an operation of the controlleraccording to Embodiment 6 of the present invention;

FIG. 30 is a flowchart illustrating an operation of the controlleraccording to Embodiment 6 of the present invention;

FIG. 31 is a timing chart illustrating operation timings of aconventional device as illustrated in Japanese Patent No. 4214401; and

FIG. 32 is a timing chart illustrating operation timings of theconventional device as illustrated in Japanese Patent No. 4214401.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention are described withreference to the attached drawings.

Embodiment 1

FIG. 1 is a configuration diagram illustrating an automatic stop andrestart device for an engine according to Embodiment 1 of the presentinvention.

In FIG. 1, a crank shaft of an engine (internal-combustion engine) 1 tobe a source of power for a vehicle is connected to a transmission 2. Thetransmission 2 changes gears and transmits power of the engine 1 afterchanging gears. The driveline of the engine 1 is transmitted to drivingwheels of the vehicle. The transmission 2 is connected to a transmissionoperation device 3. The transmission operation device 3 changes atransmission state (gear shift) of the transmission 2 in accordance withdriver's transmission operation (lever operation or shift operation).

In addition, the crank shaft of the engine 1 is provided with a ringgear 4 that rotates together with the crank shaft. Near the ring gear 4,there are disposed a pinion gear 5 that can engage with the ring gear 4and ring gear rotation speed detection means 6 that generates a ringgear rotation detection signal 6 a that corresponds to a rotation speedof the ring gear 4 (hereinafter also referred to as “ring gear rotationspeed”).

The pinion gear 5 can move in the direction of approaching or separatingfrom the ring gear 4. In addition, the pinion gear 5 is connected to astarter 10. The pinion gear 5 is driven by the starter 10 to rotate. Inother words, if the pinion gear 5 engages with the ring gear 4, theengine 1 is cranked when the pinion gear 5 is driven by the starter 10to rotate.

The transmission 2, the transmission operation device 3, the ring gearrotation speed detection means 6, and the starter 10 are electricallyconnected to the controller 100. The controller 100 performs anautomatic stop process for the engine 1 if a predetermined automaticengine stop condition is satisfied, and after that, if a predeterminedrestart condition is satisfied, the controller 100 performs a restartprocess for the engine 1. In other words, the controller 100 performs anautomatic engine stop and restart process. In addition, the controller100 includes starter drive unit (starter driving circuit) 101 fordriving the starter 10.

In addition, the controller 100 receives a transmission state signal 2 athat is a signal indicating a transmission state of the transmission 2from the transmission 2. In addition, the controller 100 receives atransmission operation state signal 3 a that is a signal indicating astate of the transmission operation device 3 (lever position) from thetransmission operation device 3. Further, the controller 100 receivesthe ring gear rotation detection signal 6 a from the ring gear rotationspeed detection means 6. Note that the controller 100 may control thetransmission state of the transmission 2 in accordance with atransmission operation of the transmission operation device 3 by thedriver.

Next, a configuration of the starter 10 is described more specifically.FIG. 2 is a configuration diagram illustrating the starter 10illustrated in FIG. 1. In FIG. 2, the starter 10 includes a startermotor 11 that drives the pinion gear 5 to rotate, and pinion gear thrustmeans 12 that moves the pinion gear 5 in the direction of approaching orseparating from the ring gear 4.

The drive of the starter motor 11 is controlled by a starter drivesignal 100 a from the controller 100 (starter drive unit 101) (if thesignal 100 a is ON, the starter motor 11 is driven). The drive of thepinion gear thrust means 12 is controlled by a pinion gear thrust signal100 b from the controller 100 (if the signal 100 b is ON, the piniongear 5 is thrusted).

Here, the transmission 2, the transmission operation device 3, the ringgear 4, the pinion gear 5, the starter motor 11, the pinion gear thrustmeans 12, and the ring gear rotation speed detection means 6 constitutea start and transmission system of the vehicle.

Next, a configuration of the controller 100 is described morespecifically. FIG. 3 is a block diagram illustrating the controller 100illustrated in FIG. 1. Note that the starter drive unit 101 is omittedin FIG. 3. In FIG. 3, the controller 100 includes starter motor drivetime measurement means 102, pinion gear rotation speed estimation means103, a subtractor 104, first pinion gear thrust timing determinationmeans 105, second pinion gear thrust timing determination means 106,transmission state determination means 107, and a state selection switch108.

The starter motor drive time measurement means 102 measures startermotor drive time that is drive time from start of driving the startermotor 11. The pinion gear rotation speed estimation means 103 estimatesa rotation speed of the pinion gear 5 (hereinafter also referred to as“pinion gear rotation speed”) based on the starter motor drive timemeasured by the starter motor drive time measurement means 102.

The subtractor 104 subtracts the rotation speed of the pinion gear 5estimated by the pinion gear rotation speed estimation means 103 fromthe rotation speed of the ring gear 4 of the ring gear rotationdetection signal 6 a. In other words, the subtractor 104 calculates arotation speed difference between the ring gear 4 and the pinion gear 5(hereinafter referred to as a “difference between the ring gear rotationspeed and the pinion gear rotation speed”).

The first pinion gear thrust timing determination means 105 determines athrust timing of the pinion gear 5 based on the rotation speeddifference between the ring gear 4 and the pinion gear 5 calculated bythe subtractor 104. The second pinion gear thrust timing determinationmeans 106 determines a thrust timing of the pinion gear 5, similarly tothe first pinion gear thrust timing determination means 105, based onthe rotation speed difference between the ring gear 4 and the piniongear 5 calculated by the subtractor 104.

The transmission state determination means 107 monitors states of thetransmission 2 and the transmission operation device 3 using thetransmission state signal 2 a and the transmission operation statesignal 3 a, so as to determine a state of the transmission 2. Inaddition, the transmission state determination means 107 switchescontacts of the state selection switch 108 in accordance with thedetermined state of the transmission 2.

Specifically, if the determined state of the transmission 2 is a driverange (hereinafter also referred to as a “D range”), the transmissionstate determination means 107 switches contacts of the state selectionswitch 108 so as to drive the pinion gear thrust means 12 at a timingdetermined by the first pinion gear thrust timing determination means105. If the determined state of the transmission 2 is a non-drive range(hereinafter also referred to as an “N range”), the transmission statedetermination means 107 switches contacts of the state selection switch108 so as to drive the pinion gear thrust means 12 at a timingdetermined by the second pinion gear thrust timing determination means106.

Here, the controller 100 may include a computer (not shown) includingprocessing unit (CPU), storage unit (ROM, RAM, or the like), and signalinput and output unit. The storage means of the computer of thecontroller 100 stores programs for realizing functions of the starterdrive unit 101, the starter motor drive time measurement means 102, thepinion gear rotation speed estimation means 103, the subtractor 104, thefirst pinion gear thrust timing determination means 105, the secondpinion gear thrust timing determination means 106, the transmissionstate determination means 107, and the state selection switch 108.

Next, operation timings of the controller 100 are described. FIG. 4 is atiming chart illustrating operation timings of the automatic engine stopand restart process of the controller 100 illustrated in FIG. 1. In FIG.4, the ring gear rotation speed is represented by reference numeral 201;and the pinion gear rotation speed, 202. In addition, an automaticengine stop flag indicating that the automatic engine stop condition issatisfied is represented by reference numeral 203, and an engine restartflag indicating that an engine restart condition is satisfied, 204.Further, the starter drive signal 100 a, 205; the pinion gear thrustsignal 100 b, 206; and the transmission state, 207.

First, at a time point t1, the automatic engine stop condition issatisfied, and the controller 100 starts a stop process for the engine1. After that, the engine restart condition is satisfied at a time pointt2. As a result, the controller 100 turn on the starter drive signal 100a so as to start the pinion gear 5 to rotate.

At a time point t3, the transmission state is changed from the driverange to the non-drive range. As a result, decrease ratio of the enginerotation speed increases or decreases from the decrease ratio in thecase of the drive range. Note that if the transmission state is notchanged from the drive range to the non-drive range at the time pointt3, the ring gear rotation speed 201 indicates decreasing characteristicas illustrated by a broken line in FIG. 4.

At a time point t4, a difference ΔN between the ring gear rotation speedand the pinion gear rotation speed becomes equal to a predeterminedvalue (predetermined speed difference). Therefore, the controller 100predicts that the ring gear rotation speed and the pinion gear rotationspeed are synchronized with each other after a pinion gear abutmentdelay time ΔT, and turns on the pinion gear thrust signal 100 b.

Then, at time point t5, the ring gear rotation speed and the pinion gearrotation speed are synchronized with each other, and simultaneously thepinion gear 5 abuts against the ring gear 4 so that the pinion gear 5engages with the ring gear 4. After that, the controller 100 controlsthe pinion gear 5 to rotate so as to drive the ring gear 4. Then, theengine 1 is cranked so that the engine 1 can be restarted.

Here, the pinion gear abutment delay time ΔT can be determinedexperimentally in advance and can be stored in the controller 100 inadvance. For instance, it is possible to make settings so that thepinion gear thrust change quantity can be detected and to define timenecessary for the pinion gear thrust change quantity to become constantafter the pinion gear thrust signal 100 b is turned on as the piniongear abutment delay time ΔT. In addition, the controller 100 refers to amap as illustrated in FIG. 5 that is stored in the controller 100 inadvance, and hence a pinion gear rotation speed corresponding to lapsethe time from the time point of the start of driving the starter isestimated.

In this way, the controller 100 can estimate a current pinion gearrotation speed and a pinion gear rotation speed increase amount ΔN_(P)in the pinion gear abutment delay time ΔT from the present. In the samemanner as this, a speed decrease amount of the ring gear rotation speedwhile the engine is stopped and the D range is selected and a speeddecrease amount of the ring gear rotation speed while the engine isstopped and the N range is selected may be determined in advance, andthese speed decrease amounts may be stored in the controller 100 inadvance. Thus, a ring gear rotation speed decrease amount ΔN_(ED) afterthe pinion gear abutment delay time ΔT has passed when the D range isselected and a ring gear rotation speed decrease amount ΔN_(En) afterthe pinion gear abutment delay time ΔT has passed when the N range isselected can be estimated.

In the case where a difference ΔN between the current ring gear rotationspeed and the pinion gear rotation speed becomes equal to a sum of thepinion gear rotation speed increase amount ΔN after the pinion gearabutment delay time ΔT has passed and the ring gear rotation speeddecrease amount ΔN_(EN) after the pinion gear abutment delay time ΔT haspassed when the N range is selected, which are estimated as describedabove, when the controller 100 starts to thrust the pinion gear 5, thepinion gear rotation speed and the ring gear rotation speed can besynchronized with each other at the timing when the pinion gear 5 andthe ring gear 4 abut against each other. Note that the same is true forthe case where the D range is selected.

In addition, the first pinion gear thrust timing determination means 105and the second pinion gear thrust timing determination means 106 myrefer to the map as illustrated in FIG. 6 based on the ring gearrotation speed and the pinion gear rotation speed so that the piniongear thrust timing is determined.

In FIG. 6, a first pinion gear thrust timing determination map that isused by the first pinion gear thrust timing determination means 105 whenthe transmission state is the D range is represented by referencenumeral 301; and a second pinion gear thrust timing determination mapthat is used by the second pinion gear thrust timing determination means106 when the transmission state is the N range, 302.

Therefore, the first pinion gear thrust timing determination means 105determines the pinion gear thrust timing corresponding to the speeddecrease amount of the ring gear rotation speed when the transmission 2is in the drive range (D range). In contrast, the second pinion gearthrust timing determination means 106 determines the pinion gear thrusttiming corresponding to the speed decrease amount of the ring gearrotation speed when the transmission 2 is in the non-drive range (Nrange).

Next, an operation of the controller 100 in the automatic engine stopand restart process according to Embodiment 1 is described. FIGS. 7 to11 are flowcharts illustrating an operation of the controller 100illustrated in FIG. 1. Note that the operation illustrated in FIGS. 7 to11 is performed by the controller 100 at a constant period. In addition,FIGS. 7 and 8 are connected with each other at the nodes A and B, andFIGS. 8 and 9 are connected with each other at the nodes C and D.Further, FIGS. 9 and 10 are connected with each other at the nodes E andF, and FIGS. 10 and 11 are connected with each other at the nodes G andH.

In FIGS. 7 to 11, first, in Step S100 of FIG. 7, the controller 100determines the current state. In this case, if the current state is“during engine rotation”, the process flow of the controller 100 goes toStep S101 in FIG. 7. In addition, if the current state is “during idlestop”, the process flow of the controller 100 goes to Step S111 in FIG.7. Further, if the current state is “during pinion gear thrust”, theprocess flow of the controller 100 goes to Step S121 in FIG. 8.

In addition, if the current state is “during engine stop process”, theprocess flow of the controller 100 goes to Step S131 in FIG. 8. Inaddition, if the current state is “during cranking”, the process flow ofthe controller 100 goes to Step S141 in FIG. 9. Further, if the currentstate is “during the D range restart”, the process flow of thecontroller 100 goes to Step S151 in FIG. 9.

In addition, if the current state is “during the D range restart andduring pinion gear thrust”, the process flow of the controller 100 goesto Step S161 in FIG. 10. In addition, if the current state is “duringthe N range restart”, the process flow of the controller 100 goes toStep S171 in FIG. 10. Further, if the current state is “during the Nrange restart and during pinion gear thrust”, the process flow of thecontroller 100 goes to Step S181 in FIG. 11.

If the current state is “during engine rotation”, the controller 100checks whether or not there is a request for the automatic engine stopin Step S101 of FIG. 7. If there is no request for the automatic enginestop, the current task process is finished, and the process flow goes toStep S100 after a constant period of time. On the contrary, if there isa request for the automatic engine stop, the process flow of thecontroller 100 goes to Step S102. In Step S102, the controller 100changes the current state to “during engine stop process”, finishes thecurrent task process, and goes to the process of Step S100 after aconstant period of time.

If the current state is “during idle stop”, the controller 100 checkswhether or not there is not a request for the engine restart in StepS111 of FIG. 7. If there is no request for the engine restart, thecurrent task process is finished, and the process flow goes to Step S100after a constant period of time. On the contrary, if there is a requestfor the engine restart, the process flow of the controller 100 goes toStep S112. In Step S112, the controller 100 turns on the pinion gearthrust signal 100 b and goes to the process of Step S113. In Step S113,the controller 100 changes the current state to “during pinion gearthrust” and finishes the current task process. Then, the process flowgoes to Step S100 after a constant period of time.

If the current state is “during pinion gear thrust”, the controller 100checks whether or not the pinion gear abutment delay time has passed inStep S121 of FIG. 8. If the pinion gear abutment delay time has notpassed, the current task process is finished, and the process flow goesto Step S100 after a constant period of time. On the contrary, if thepinion gear abutment delay time has passed, the process flow of thecontroller 100 goes to Step S122. In Step S122, the controller 100 turnson the starter drive signal 100 a, and the process flow goes to StepS123. In Step S113, the controller 100 changes the current state to“during cranking”, the current task process is finished, and the processflow goes to Step S100 after a constant period of time.

If the current state is “during engine stop process”, the controller 100checks whether or not there is a request for engine restart in Step S131of FIG. 8. If there is no request for the engine restart, the processflow goes to Step S132. The controller 100 checks whether or not theengine 1 is stopped in Step S132. If the engine 1 is not stopped, thecurrent task process is finished, and the process flow goes to Step S100after a constant period of time.

On the contrary, if the engine 1 is stopped, the process flow of thecontroller 100 goes to Step S133. In Step S133, the controller 100changes the current state to “during idle stop”, finishes the currenttask process, and goes to the process of Step S100 after a constantperiod of time.

In addition, if there is a request for the engine restart in Step S131of FIG. 8, the process flow of the controller 100 goes to Step S134. InStep S134, the controller 100 turns on the starter drive signal 100 a,the process flow goes to Step S135. In Step S135, the controller 100changes the current state to “during the D range restart”, the currenttask process is finished, and the process flow goes to Step S100 after aconstant period of time.

If the current state is “during cranking”, the controller 100 checkswhether or not complete explosion has been performed for the engine 1(whether or not the engine 1 is in an idle state) in Step S141 of FIG.9. If complete explosion has not been performed for the engine 1, thecurrent task process is finished, and the process flow goes to Step S100after a constant period of time.

On the contrary, if complete explosion has been performed for the engine1, the controller 100 performs the process of Steps S142 and S143. InSteps S142 and S143, the controller 100 turns off the starter drivesignal 100 a, and turns off the pinion gear thrust signal 100 b. Then,the process flow goes to Step S144. In Step S144, the controller 100changes the current state to “during engine rotation”, the current taskprocess is finished, and the process flow goes to Step S100 after aconstant period of time.

If the current state is “during D range restart”, the controller 100checks whether or not the transmission operation device 3 is changed tothe N range by the driver in Step S151 of FIG. 9. If the transmissionoperation device 3 is not changed to the N range, the process flow goesto Step S152. In Step S152, the controller 100 calculates a rotationspeed difference between the ring gear 4 and the pinion gear 5, and theprocess flow goes to Step S153.

In Step S153, the controller 100 checks whether or not the rotationspeed difference between the ring gear 4 and the pinion gear 5 is closeto a first predetermined value (value determined by the first piniongear thrust timing determination means 105). If the rotation speeddifference is not close to the first predetermined value, the currenttask process is finished, and the process flow goes to Step S100 after aconstant period of time.

On the contrary, if the rotation speed difference between the ring gear4 and the pinion gear 5 is close to the first predetermined value, theprocess flow of the controller 100 goes to Step S154. In Step S154, thecontroller 100 turns on the pinion gear thrust signal 100 b, and theprocess flow goes to Step S155. In Step S155, the controller 100 changesthe current state to “during D range restart and during pinion gearthrust”, the current task process is finished, and the process flow goesto Step S100 after a constant period of time.

In addition, if the transmission operation device 3 is changed to the Nrange in Step S151 of FIG. 9, the process flow of the controller 100goes to Step S156. In Step S156, the controller 100 changes the currentstate to “during the N range restart”, the current task process isfinished, and the process flow goes to Step S100 after a constant periodof time.

If the current state is “during the D range restart and during piniongear thrust”, the controller 100 checks whether or not the pinion gearabutment delay time has passed in Step S161 of FIG. 10. If the piniongear abutment delay time has not passed, the controller 100 finishes thecurrent task process, and the process flow goes to Step S100 after aconstant period of time.

On the contrary, if the pinion gear abutment delay time has passed, theprocess flow of the controller 100 goes to Step S162. In Step S162, thecontroller 100 changes the current state to “during cranking”, thecurrent task process is finished, and the process flow goes to Step S100after a constant period of time.

If the current state is “during N range restart”, the controller 100calculates a rotation speed difference between the ring gear 4 and thepinion gear 5 in Step S171 of FIG. 10, and the process flow goes to StepS172. In Step S172, the controller 100 checks whether or not therotation speed difference between the ring gear 4 and the pinion gear 5is close to a second predetermined value (value determined by the secondpinion gear thrust timing determination means 106). If the rotationspeed difference is not close to the second predetermined value, thecontroller 100 finishes the current task process, and the process flowgoes to Step S100 after a constant period of time.

On the contrary, if the rotation speed difference between the ring gear4 and the pinion gear 5 is close to the second predetermined value, theprocess flow of the controller 100 goes to Step S173. In Step S173, thecontroller 100 turns on the pinion gear thrust signal 100 b, and theprocess flow goes to Step S174. In Step S174, the controller 100 changesthe current state to “during N range restart and during pinion gearthrust”, the current task process is finished, and the process flow goesto Step S100 after a constant period of time.

If the current state is “during the N range restart and during piniongear thrust”, the controller 100 checks whether or not the pinion gearabutment delay time has passed in Step S181 of FIG. 11. If the piniongear abutment delay time has not passed, the current task process isfinished, and the process flow goes to Step S100 after a constant periodof time.

On the contrary, if the pinion gear abutment delay time has passed, theprocess flow of the controller 100 goes to Step S182. In Step S182, thecontroller 100 changes the current state to “during cranking”, thecurrent task process is finished, and the process flow goes to Step S100after a constant period of time.

According to the automatic stop and restart device for an engine ofEmbodiment 1 as described above, the controller 100 controls drive ofthe pinion gear thrust means 12 by using two types of pinion gear thrusttimings, including the pinion gear thrust timing corresponding to thespeed decrease amount of the ring gear rotation speed when thetransmission 2 is in the drive range and the pinion gear thrust timingcorresponding to the speed decrease amount of the ring gear rotationspeed when the transmission 2 is in the non-drive range. With thisconfiguration, the pinion gear 5 does not abut against the ring gear 4in the state where the ring gear rotation speed and the pinion gearrotation speed are not synchronized with each other. Therefore, even ifthe engine restart condition is satisfied during the automatic enginestop process and the transmission state is changed during the enginerestart process after that, occurrence of an abnormal condition such asnoise or a breakdown can be suppressed while the engine restart processis performed. In addition, the operation in accordance with the driver'sintention is secured, and hence unnatural feeling to the driver can beeliminated.

Embodiment 2

In Embodiment 1, the two types of pinion gear thrust timings are usedfor the controller 100 to control drive of the pinion gear thrust means12, and hence occurrence of an abnormal condition such as noise or abreakdown can be suppressed when the transmission state is changedduring the engine restart process. In contrast, in Embodiment 2, thecontroller 100 controls the transmission state of the transmission 2 soas to suppress occurrence of an abnormal condition such as noise or abreakdown when the transmission state is changed during the enginerestart process. A configuration of Embodiment 2 is the same as that ofEmbodiment 1, but the operation timings of the controller 100 aredifferent between Embodiment 1 and Embodiment 2.

Next, the operation timings of the controller 100 of Embodiment 2 aredescribed. FIG. 12 is a timing chart illustrating the operation timingsof the controller 100 in the automatic engine stop and restart processaccording to Embodiment 2 of the present invention. In FIG. 12, the ringgear rotation speed is represented by reference numeral 201; and thepinion gear rotation speed, 202. In addition, the automatic engine stopflag indicating that the automatic engine stop condition is satisfied isrepresented by reference numeral 203; and the engine restart flagindicating that the engine restart condition is satisfied, 204. Further,the starter drive signal 100 a is represented by reference numeral 205;and the pinion gear thrust signal 100 b, 206. In addition, thetransmission state is represented by reference numeral 207; and thetransmission operation device state, 208.

First, at a time point t1, the automatic engine stop condition issatisfied, and the controller 100 starts a stop process for the engine1. After that, the engine restart condition is satisfied at a time pointt2. As a result, the controller 100 turn on the starter drive signal 100a so as to start the pinion gear 5 to rotate.

At a time point t3, the driver performs the transmission operation, andhence the transmission operation device state is set to the non-driverange. In contrast, the controller 100 maintains the transmission stateto be the drive range, and hence the engine restart process iscontinued. Then, at a time point t4, the difference ΔN between the ringgear rotation speed and the pinion gear rotation speed becomes close toa predetermined value. Therefore, the controller 100 predicts that thering gear rotation speed and the pinion gear rotation speed aresynchronized with each other after the pinion gear abutment delay timeΔT, and turns on the pinion gear thrust signal 100 b.

At a time point t5, the ring gear rotation speed and the pinion gearrotation speed are synchronized with each other, and simultaneously thepinion gear 5 abuts against and engages with the ring gear 4. On thisoccasion, the controller 100 changes the transmission state to thenon-drive range. During the period from the time point t3 to the timepoint t5, the controller 100 may control display means for indicating atransmission shift on an instrument panel or the like to display thenon-drive range or perform blinking so as to indicate that the state ischanging. After that, the controller 100 controls the pinion gear 5 torotate so as to drive the ring gear 4. Thus, the engine 1 is cranked andis restarted.

Therefore, if the transmission operation device 3 accepts thetransmission operation in the engine restart process during theautomatic engine stop, the controller 100 of Embodiment 2 prioritizesthe engine restart process and performs the transmission operation ofthe transmission 2 (changes the transmission range) after the engine 1restarts. In other words, if the transmission operation device 3 acceptsthe transmission operation in the engine restart process during theautomatic engine stop, the controller 100 of Embodiment 2 switches thetransmission state of the transmission 2 with delay as illustrated by ADin FIG. 12.

Next, an operation of the controller 100 in the automatic engine stopand restart process of Embodiment 2 is described. Here, an overview ofthe operation of the controller 100 of Embodiment 2 is the same as thatof Embodiment 1. The operation in the case where the current state is“during D range restart”, the operation in the case where the currentstate is “during N range restart”, and the operation in the case wherethe current state is “during N range restart and during pinion gearthrust” are different between Embodiment 1 and Embodiment 2. Here,differences between Embodiment 1 and Embodiment 2 are mainly described.

FIGS. 13 to 15 are flowcharts illustrating the operation of thecontroller 100 according to Embodiment 2 of the present invention. Notethat FIG. 13 is connected with FIG. 8 of Embodiment 1 at the nodes C andD. In addition, FIGS. 13 and 14 are connected with each other at thenodes E and F. Further, FIGS. 14 and 15 are connected with each other atthe nodes G and H.

If the current state is “during D range restart”, the controller 100checks whether or not the driver has changed the transmission operationdevice 3 to the N range in Step S151 of FIG. 13. If the transmissionoperation device 3 is not changed to the N range, the process flow goesto Step S152. The operation in the case where the transmission operationdevice 3 is not changed to the N range is the same as that of Embodiment1.

On the contrary, if the transmission operation device 3 is changed tothe N range, the process flow of the controller 100 goes to Step S256.In Step S256, the controller 100 hold the range switching of thetransmission 2 (maintains the transmission 2 in the D range) and startsblinking of the indicator (not shown), and the process flow goes to StepS257. In Step S257, the controller 100 changes the current state to“during N range restart”, and the current task process is finished.Then, the process flow goes to Step S100 after a constant period oftime.

If the current state is “during N range restart”, the controller 100calculates the rotation speed difference between the ring gear 4 and thepinion gear 5 in Step S171 of FIG. 14, and the process flow goes to StepS272. In Step S272, the controller 100 checks whether or not therotation speed difference between the ring gear 4 and the pinion gear 5is close to the first predetermined value (value determined by the firstpinion gear thrust timing determination means 105). If the rotationspeed difference is not close to the first predetermined value, thecurrent task process is finished, and the process flow goes to Step S100after a constant period of time.

On the contrary, if the rotation speed difference between the ring gear4 and the pinion gear 5 is close to the first predetermined value, theprocess flow of the controller 100 goes to Step S273. In Step S273, thecontroller 100 turns on the pinion gear thrust signal 100 b, and theprocess flow goes to Step S274. In Step S274, the controller 100 changesthe current state to “during N range restart and during pinion gearthrust”, and the current task process is finished. Then, the processflow goes to Step S100 after a constant period of time.

Here, in Embodiment 1, two types of predetermined values including thefirst predetermined value and the second predetermined value are used asillustrated in S153 of FIG. 9 or 5172 in FIG. 10. In contrast, inEmbodiment 2, the transmission state is not changed until the controller100 completes the restart process even if the transmission operation isperformed in the engine restart process during the automatic enginestop. Thus, even if the transmission operation device 3 accepts thetransmission operation, the controller 100 maintains the transmission 2in the D range, and hence the decrease ratio of the rotation of the ringgear 4 is not changed. Therefore, only one type of predetermined value,that is, the first predetermined value can be used.

If the current state is “during the N range restart and during piniongear thrust”, the controller 100 checks whether or not the pinion gearabutment delay time has passed in Step S181 of FIG. 15. If the piniongear abutment delay time has not passed, the current task process isfinished, and the process flow goes to Step S100 after a constant periodof time. On the contrary, if the pinion gear abutment delay time haspassed, the process flow of the controller 100 goes to Step S282.

In Step S282, the controller 100 switches the transmission 2 to the Nrange, and the process flow goes to Step S283. In Step S283, thecontroller 100 stops blinking of the indicator, and the process flowgoes to Step S284. In Step S284, the controller 100 changes the currentstate to “during cranking”, and the current task process is finished.Then, the process flow goes to Step S100 after a constant period oftime. Other operations are the same as those of Embodiment 1.

According to the automatic stop and restart device for an engine ofEmbodiment 2 as described above, even if the transmission operation isperformed in the engine restart process during the automatic enginestop, the transmission state is not changed until the controller 100finishes the restart process. With this configuration, no change occursin the decrease amount of the engine rotation speed due to transmissionoperation. Therefore, a difference of synchronizing timing between thepinion gear rotation speed and the ring gear rotation speed does notoccur so that the pinion gear 5 and the ring gear 4 can engage with eachother. As a result, occurrence of an abnormal condition such as noise ora breakdown can be suppressed when the engine restart process isperformed.

In addition, compared with the case where the transmission 2 is in the Nrange, the influence of a load of the generator or the like is smallwith little variation, and hence the engine 1 can be restarted moresecurely.

Embodiment 3

In Embodiment 1, the two types of pinion gear thrust timings are usedfor the controller 100 to control drive of the pinion gear thrust means12, and hence occurrence of an abnormal condition such as noise or abreakdown can be suppressed when the transmission state is changedduring the engine restart process. In contrast, in Embodiment 3, in acase where the pinion gear 5 and the ring gear 4 cannot engage with eachother, the controller 100 stops the engine restart process so as tosuppress occurrence of an abnormal condition such as noise or abreakdown when the transmission state is changed during the enginerestart process. A configuration of Embodiment 3 is the same as that ofEmbodiment 1, but the operation timings of the controller 100 aredifferent between Embodiment 1 and Embodiment 3.

Next, the operation timings of the controller 100 of Embodiment 3 aredescribed. FIG. 16 is a timing chart illustrating the operation timingsof the controller 100 in the automatic engine stop and restart processaccording to Embodiment 3 of the present invention. In FIG. 16, the ringgear rotation speed is represented by reference numeral 201; and thepinion gear rotation speed, 202. In addition, the automatic engine stopflag indicating that the automatic engine stop condition is satisfied isrepresented by reference numeral 203; and the engine restart flagindicating that the engine restart condition, 204. Further, the starterdrive signal 100 a is represented by reference numeral 205; and thepinion gear thrust signal 100 b, 206. In addition, the transmissionstate is represented by reference numeral 207.

First, at a time point t1, the automatic engine stop condition issatisfied, and the controller 100 starts a stop process for the engine1. After that, the engine restart condition is satisfied at a time pointt2. As a result, the controller 100 turn on the starter drive signal 100a so as to start the pinion gear 5 to rotate.

At a time point t3, the transmission state is changed to the non-driverange. At the same time, the controller 100 turns off the starter drivesignal 100 a (stops the signal output). Note that if the pinion gearthrust signal 100 b is ON, the controller 100 turns off the starterdrive signal 100 a and also turns off the pinion gear thrust signal 100b. Therefore, the controller 100 of Embodiment 3 stops the enginerestart process.

Next, an operation of the automatic engine stop and restart process ofthe controller 100 of Embodiment 3 is described. Here, an overview ofthe operation of the controller 100 of Embodiment 3 is the same as thatof Embodiment 1. The operation in the case where the current state is“during D range restart” and the operation in the case where the currentstate is “during D range restart and during pinion gear thrust” aredifferent between Embodiment 1 and Embodiment 3. In addition, inEmbodiment 3, the operation in the case of “during N range restart” andthe operation in the case of “during N range restart and during piniongear thrust” in Embodiment 1 are omitted unlike Embodiment 1. Here, thedifference between Embodiment 1 and Embodiment 3 is described mainly.

FIGS. 17 and 18 are flowcharts illustrating the operation of thecontroller 100 according to Embodiment 3 of the present invention. Notethat FIG. 17 is connected with FIG. 8 of Embodiment 1 at the nodes C andD. In addition, FIGS. 17 and 18 are connected with each other at thenodes E and F.

If the current state is “during D range restart”, the controller 100checks whether or not the driver has changed the transmission operationdevice 3 to the N range in Step S151 of FIG. 17. If the transmissionoperation device 3 is not changed to the N range, the process flow goesto Step S152. The operation in the case where the transmission operationdevice 3 is not changed to the N range is the same as that of Embodiment1.

On the contrary, if the transmission operation device 3 is changed tothe N range, the process flow of the controller 100 goes to Step S356.In Step S356, the controller 100 turns off the starter drive signal 100a, and the process flow goes to Step S357. In Step S357, the controller100 changes the current state to “during idle stop”, and the currenttask process is finished. Then, the process flow goes to Step S100 aftera constant period of time.

If the current state is “during D range restart and during pinion gearthrust”, the controller 100 checks whether or not the pinion gearabutment delay time has passed in Step S161 of FIG. 18. If the piniongear abutment delay time has passed, the process flow goes to Step S162.In Step S162, the controller 100 changes the current state to “duringcranking”, and the current task process is finished. Then, the processflow goes to Step S100 after a constant period of time.

On the contrary, if the pinion gear abutment delay time has not passed,the process flow of the controller 100 goes to Step S363. In Step S363,the controller 100 checks whether or not the driver has changed thetransmission operation device 3 to the N range. If the transmissionoperation device 3 is not changed to the N range, the current taskprocess is finished. Then, the process flow goes to Step S100 after aconstant period of time.

In Step S363, if the transmission operation device 3 is changed to the Nrange, the process flow of the controller 100 goes to Steps S364 andS365. In Steps S364 and S365, the controller 100 turns off the starterdrive signal 100 a and turns off the pinion gear thrust signal 100 b.Then, the process flow goes to Step S366. In Step S366, the controller100 changes the current state to “during idle stop”, and the currenttask process is finished. Then, the process flow goes to Step S100 aftera constant period of time. Other operations are the same as those ofEmbodiment 1.

According to the automatic stop and restart device for an engine ofEmbodiment 3 as described above, the controller 100 stops the enginerestart process in the state where the pinion gear 5 and the ring gear 4cannot engage with each other when the transmission operation isperformed in the engine restart process during the automatic enginestop. Thus, occurrence of an abnormal condition such as noise or abreakdown can be prevented more securely.

Embodiment 4

In Embodiment 3, if the pinion gear 5 and the ring gear 4 cannot engagewith each other, the controller 100 stops the engine restart process. Incontrast, in Embodiment 4, if the pinion gear 5 and the ring gear 4cannot engage with each other, the controller 100 stops the enginerestart process and after the stopping, performs the engine restartprocess again. An overview of the configuration of Embodiment 4 is thesame as that of Embodiment 1, but operation timings of the controller100 of Embodiment 4 are different from those of Embodiments 1 and 3.

Next, the operation timings of the controller 100 of Embodiment 4 aredescribed. FIG. 19 is a timing chart illustrating the operation timingsof the controller 100 in the automatic engine stop and restart processaccording to Embodiment 4 of the present invention. In FIG. 19, the ringgear rotation speed is represented by reference numeral 201; and thepinion gear rotation speed, 202. In addition, the automatic engine stopflag indicating that the automatic engine stop condition is satisfied isrepresented by reference numeral 203; and the engine restart flagindicating that the engine restart condition is satisfied, 204. Further,the starter drive signal 100 a is represented by reference numeral 205;and the pinion gear thrust signal 100 b, 206. In addition, thetransmission state is represented by reference numeral 207.

First, at a time point t1, the automatic engine stop condition issatisfied, and the controller 100 starts a stop process for the engine1. After that, the engine restart condition is satisfied at a time pointt2. As a result, the controller 100 turn on the starter drive signal 100a so as to start the pinion gear 5 to rotate.

At a time point t3, the transmission state is changed to the non-driverange. At the same time, the controller 100 turns off the starter drivesignal 100 a (stops the signal output). Note that if the pinion gearthrust signal 100 b is ON, the controller 100 turns off the starterdrive signal 100 a and also turns off the pinion gear thrust signal 100b.

At a time point t4, rotation of the engine 1 is stopped. Then, at a timepoint t5, the controller 100 turns on the pinion gear thrust signal 100b. This operation of the controller 100 turning on the pinion gearthrust signal 100 b at the time point t5 is performed because timeΔT_(S) that is predicted to be necessary for stopping rotation of thepinion gear passes from the time point t3 as a starter drive stop timepoint to a time point t6 when the pinion gear thrust delay time ΔT haspassed from the time point t5. Note that time calculated by subtractingthe pinion gear thrust delay time ΔT from the time ΔT_(S) is a restartinhibit time.

At the time point t6, the pinion gear 5 abuts against the ring gear 4,and the controller 100 turns on the starter drive signal 100 a. Then,the pinion gear 5 is caused to engage with the ring gear 4 so as todrive the ring gear 4. Thus, the engine 1 is cranked and is restarted.Therefore, the controller 100 of Embodiment 4 stops the engine restartprocess and after the stopping, performs the engine restart processagain.

Next, an operation of the controller 100 in the automatic engine stopand restart process of Embodiment 4 is described. Here, an overview ofthe operation of the controller 100 of Embodiment 4 is the same as thatof Embodiment 1. The operation in the case where the current state is“during D range restart” and the operation in the case where the currentstate is “during D range restart and during pinion gear thrust” aredifferent between Embodiment 1 and Embodiment 4. In addition, Embodiment4 is different from Embodiment 1 also in that the operation of “duringgear rotation stop and wait” and the operation of “during gear rotationstop and wait and during pinion gear thrust” are performed instead ofthe operation in the case of “during N range restart” and the operationin the case of “during N range restart and during pinion gear thrust” inEmbodiment 1. Here, the difference from Embodiment 1 is describedmainly.

FIGS. 20 to 22 are flowcharts illustrating the operation of thecontroller 100 according to Embodiment 4 of the present invention. Notethat FIG. 20 is connected with FIG. 8 of Embodiment 1 at the nodes C andD. In addition, FIGS. 20 and 21 are connected with each other at thenodes E and F. Further, FIGS. 21 and 22 are connected with each other atthe nodes G and H.

If the current state is “during D range restart”, the controller 100checks whether or not the driver has changed the transmission operationdevice 3 to the N range in Step S151 of FIG. 20. If the transmissionoperation device 3 is not changed to the N range, the process flow goesto Step S152. The operation in the case where the transmission operationdevice 3 is not changed to the N range is the same as that of Embodiment1.

On the contrary, if the transmission operation device 3 is changed tothe N range, the process flow of the controller 100 goes to Step S456.In Step S456, the controller 100 turns off the starter drive signal 100a, and the process flow goes to Step S457. In Step S457, the controller100 changes the current state to “during gear rotation stop and wait”,and the current task process is finished. Then, the process flow goes toStep S100 after a constant period of time.

If the current state is “during D range restart and during pinion gearthrust”, the controller 100 checks whether or not the pinion gearabutment delay time has passed in Step S161 of FIG. 21. If the piniongear abutment delay time has passed, the process flow goes to Step S162.In Step S162, the controller 100 changes the current state to “duringcranking”, and the current task process is finished. Then, the processflow goes to Step S100 after a constant period of time.

On the contrary, if the pinion gear abutment delay time has not passed,the process flow of the controller 100 goes to Step S463. In Step S463,the controller 100 checks whether or not the driver has changed thetransmission operation device 3 to the N range. If the transmissionoperation device 3 is not changed to the N range, the current taskprocess is finished. Then, the process flow goes to Step S100 after aconstant period of time.

In Step S463, if the transmission operation device 3 is changed to the Nrange, the process flow of the controller 100 goes to Steps S464 andS465. In Steps S464 and S465, the controller 100 turns off the starterdrive signal 100 a and turns off the pinion gear thrust signal 100 b.Then, the process flow goes to Step S466. In Step S466, the controller100 changes the current state to “during gear rotation stop and wait”,and the current task process is finished. Then, the process flow goes toStep S100 after a constant period of time.

If the current state is “during gear rotation stop and wait”, thecontroller 100 checks in Step S471 of FIG. 21 whether or not it ispredicted that the rotation of the ring gear 4 is stopped after passingof the pinion gear abutment delay time. If it is predicted that therotation of the ring gear 4 is not stopped, the current task process isfinished, and the process flow goes to Step S100 after a constant periodof time. On the contrary, if it is predicted that the rotation of thering gear 4 is stopped, the process flow of the controller 100 goes toStep S472.

In Step S472, if a constant time (e.g., 1,500 msec) has not passed froma starter motor drive stop time point after passing of the pinion gearabutment delay time (that is, if it is predicted that the rotation ofthe pinion gear 5 is not stopped), the controller 100 finishes thecurrent task process. Then, the process flow goes to Step S100 after aconstant period of time.

On the contrary, if the constant time has passed from the starter motordrive stop time point after passing of the pinion gear abutment delaytime (that is, if it is predicted that the rotation of the pinion gear 5is stopped), the process flow of the controller 100 goes to Step S473.In Step S473, the controller 100 turns on the pinion gear thrust signal100 b, and the process flow goes to Step S474. In Step S474, thecontroller 100 changes the current state to “during gear rotation stopand wait and during pinion gear thrust”, and the current task process isfinished. Then, the process flow goes to Step S100 after a constantperiod of time.

If the current state is “during gear rotation stop and wait and duringpinion gear thrust”, the controller 100 checks whether or not the piniongear abutment delay time has passed in Step S181 of FIG. 22. If thepinion gear abutment delay time has not passed, the current task processis finished, and the process flow goes to Step S100 after a constantperiod of time. On the contrary, if the pinion gear abutment delay timehas passed, the process flow of the controller 100 goes to Step S482.

In Step S482, the controller 100 turns on the starter drive signal 100a, and the process flow goes to Step S483. In Step S483, the controller100 changes the current state to “during cranking”, the current taskprocess is finished, and the process flow goes to Step S100 after aconstant period of time. Other operations are the same as those ofEmbodiment 1.

According to the automatic stop and restart device for an engine ofEmbodiment 4 as described above, if the pinion gear 5 and the ring gear4 cannot engage with each other when the transmission operation isperformed in the engine restart process during the automatic enginestop, the controller 100 restarts the engine 1 after the rotations ofthe pinion gear 5 and the ring gear 4 are stopped. With thisconfiguration, occurrence of noise or a breakdown due to a failure inthe synchronization between the pinion gear rotation speed and the ringgear rotation speed can be prevented while the engine 1 can be restartedwithout a complicated operation.

Embodiment 5

In Embodiment 5, when the engine restart process is stopped, a gearrotation stop time point when both the rotation speed of the pinion gear5 and the rotation speed of the ring gear 4 become zero is predicted,and the engine restart process is performed again after the predictedgear rotation stop time point.

An overview of the configuration of the controller 100 of Embodiment 5is similar to that of Embodiment 1. However, the controller 100 ofEmbodiment 5 further includes starter motor drive stop time measurementmeans, starter motor stop pinion gear rotation speed estimation means,and gear rotation stop time point prediction means (each of them is notshown).

The starter motor drive stop time measurement means measures time fromthe drive stop time point of the starter motor 11. The starter motorstop pinion gear rotation speed estimation means estimates a pinion gearrotation speed after the drive stop of the starter motor 11 (decreasepattern of the rotation speed) based on the pinion gear rotation speedat the drive stop time point of the starter motor 11 and the startermotor drive stop time measured by the starter motor drive stop timemeasurement means. The gear rotation stop time point prediction meanspredicts a gear rotation stop time point when both the rotation speed ofthe pinion gear 5 and the rotation speed of the ring gear 4 become zeroby using maps as illustrated in FIGS. 23 and 24.

Next, operation timings of the controller 100 of Embodiment 5 aredescribed. FIG. 25 is a timing chart illustrating operation timings ofthe controller 100 in the automatic engine stop and restart processaccording to Embodiment 5 of the present invention. Similarly to FIG.19, individual elements are represented by reference numerals 201 to 207in FIG. 25. In addition, operation timings until a time point t3 in thisexample are the same as operation timings in the case illustrated inFIG. 19. Here, operation timings after a time point t4 are describedmainly.

At the time point t4, the rotation of the engine 1 is stopped. Thecontroller 100 predicts that rotations of the engine 1 and the piniongear 5 are both stopped at a time point t6 when the pinion gear abutmentdelay time ΔT passes after a time point t5, and turns on the pinion gearthrust signal 100 b at the time point t5. At the time point t6, the ringgear rotation and the pinion gear rotation are both stopped, and thepinion gear 5 abuts against the ring gear 4. In other words, the timepoint t6 is the gear rotation stop time point.

After the time point t6, the controller 100 turns on the starter drivesignal 100 a, and hence the pinion gear 5 engages with the ring gear 4.Then, the controller 100 drives the ring gear 4, and hence the engine 1is cranked and is restarted. Note that it can be predicted that thetemporal relationship between the time point t4 when the rotation of theengine 1 is stopped and the time point t6 when the rotation of thepinion gear 5 is stopped is changed oppositely.

Therefore, the controller 100 of Embodiment 5 stops the restart processduring the restart inhibit time from the drive stop time point of thestarter motor 11 to the gear rotation stop time point, and performs theengine restart process again after the restart inhibit time passes.

Next, an operation of the controller 100 in the automatic engine stopand restart process according to Embodiment 5 is described. An overviewof the operation of the controller 100 of Embodiment 5 is similar tothat of Embodiment 4. Here, only a difference between Embodiment 4 andEmbodiment 5 is described. When the controller 100 of Embodiment 5performs the process of Step S472 of FIG. 21 described in Embodiment 4,the controller 100 uses the map as illustrated in FIG. 23 for estimatingthe pinion gear rotation speed based on the pinion gear rotation speedwhen the starter motor drive is stopped and the time after the startermotor drive is stopped. Then, the controller 100 predicts whether or notthe rotation of the pinion gear 5 is stopped after the pinion gearabutment delay time. Other operations are the same as those ofEmbodiment 4.

According to the automatic stop and restart device for an engine ofEmbodiment 5 as described above, the controller 100 estimates the piniongear rotation speed from the drive stop time point of the starter motor11, and hence the timing when the rotation of the pinion gear 5 isstopped can be estimated appropriately. Thus, time necessary forrestarting the engine 1 can be shortened. In other words, in the casewhere the engine restart process is stopped and the engine restartprocess is retried thereafter, waiting time can be shortened so that theengine 1 can be restarted more promptly.

Embodiment 6

In Embodiment 5, the controller 100 estimates the timing when therotation of the pinion gear 5 is stopped and performs the engine restartprocess in synchronization with the stop timing. In contrast, inEmbodiment 6, if it is predicted that the pinion gear rotation speed andthe ring gear rotation speed are synchronized with each other in theperiod in which the pinion gear rotation speed and the ring gearrotation speed are decreasing, the controller 100 performs the enginerestart process without waiting for the rotation stop of the pinion gear5 and the ring gear 4. An overview of the configuration of Embodiment 6is similar to that of Embodiment 5, but operation timings of thecontroller 100 are different from those of Embodiment 5.

Next, the operation timings of the controller 100 of Embodiment 6 aredescribed. FIG. 26 is a timing chart illustrating the operation timingsof the controller 100 in the automatic engine stop and restart processaccording to Embodiment 6 of the present invention. Reference numerals201 to 207 of FIG. 26 are the same as those of FIG. 19.

At a time point t1, the automatic engine stop condition is satisfied,and the controller 100 starts a stop process for the engine 1. Afterthat, the engine restart condition is satisfied at a time point t2. As aresult, the controller 100 turn on the starter drive signal 100 a so asto start the pinion gear 5 to rotate.

At a time point t3, the transmission state is changed to the non-driverange. At the same time, the controller 100 turns off the starter drivesignal 100 a. Note that the controller 100 also turns off the piniongear thrust signal 100 b if the pinion gear thrust signal 100 b is ON.After that, the controller 100 estimates the pinion gear rotation speedbased on a pinion gear rotation speed N_(ST) at the time point t3 andthe lapse time from the drive stop time point of the starter motor 11.

At a time point t4, the difference ΔN between the ring gear rotationspeed and the pinion gear rotation speed becomes close to apredetermined value. Therefore, the controller 100 predicts that thering gear rotation speed and the pinion gear rotation speed aresynchronized with each other after the pinion gear abutment delay timeΔT, and turns on the pinion gear thrust signal 100 b at the time pointt4. Here, the predetermined value used for ΔN can be defined by using amap (not shown) to be referred to based on the ring gear rotation speedand the pinion gear rotation speed.

At a time point t5, the ring gear rotation speed and the pinion gearrotation speed are synchronized with each other. At the same time, thepinion gear 5 abuts against the ring gear 4 so that the pinion gear 5and the ring gear 4 engage with each other. After the time point t5, thecontroller 100 turns on the starter drive signal 100 a and drives thepinion gear 5 to rotate, to thereby drive the ring gear 4. Thus, theengine 1 is cranked, that is, is restarted.

Next, an operation of the controller 100 in the automatic engine stopand restart process of Embodiment 6 is described. An overview of theoperation of the controller 100 of Embodiment 6 is the same as that ofEmbodiment 1. The operation in the case where the current state is“during D range restart” and the operation in the case where the currentstate is “during D range restart and during pinion gear thrust” aredifferent between Embodiment 1 and Embodiment 6. In addition, Embodiment6 is different from Embodiment 1 also in that the operation of “duringgear rotation stop and wait”, the operation of “during gear rotationstop and wait and during pinion gear thrust”, and an operation of“during decrease in rotation speed and during restart pinion gearthrust” are performed instead of the operation in the case of “during Nrange restart” and the operation in the case of “during N range restartand during pinion gear thrust” in Embodiment 1. Here, the differencefrom Embodiment 1 is described mainly.

FIGS. 27 to 30 are flowcharts illustrating the operation of thecontroller 100 according to Embodiment 6 of the present invention. Notethat FIG. 27 is connected with FIG. 8 of Embodiment 1 at the nodes C andD. In addition, FIGS. 27 and 28 are connected with each other at thenodes E and F. Further, FIGS. 28 and 29 are connected with each other atthe nodes I and J. Still further, FIGS. 29 and 30 are connected witheach other at the nodes K and L.

If the current state is “during D range restart”, the controller 100checks whether or not the driver has changed the transmission operationdevice 3 to the N range in Step S151 of FIG. 27. If the transmissionoperation device 3 is not changed to the N range, the process flow goesto Step S152. The operation in the case where the transmission operationdevice 3 is not changed to the N range is the same as that of Embodiment1.

On the contrary, if the transmission operation device 3 is changed tothe N range, the process flow of the controller 100 goes to Step S556.In Step S556, the controller 100 turns off the starter drive signal 100a, and the process flow goes to Step S557. In Step S557, the controller100 changes the current state to “during gear rotation stop and wait”,and the current task process is finished. Then, the process flow goes toStep S100 after a constant period of time.

If the current state is “during D range restart and during pinion gearthrust”, the controller 100 checks whether or not the pinion gearabutment delay time has passed in Step S161 of FIG. 28. If the piniongear abutment delay time has passed, the process flow goes to Step S162.In Step S162, the controller 100 changes the current state to “duringcranking”, and the current task process is finished. Then, the processflow goes to Step S100 after a constant period of time.

On the contrary, if the pinion gear abutment delay time has not passed,the process flow of the controller 100 goes to Step S563. In Step S563,the controller 100 checks whether or not the driver has changed thetransmission operation device 3 to the N range. In this case, if thetransmission operation device 3 is not changed to the N range, thecontroller 100 finishes the current task process. Then, the process flowgoes to Step S100 after a constant period of time.

In Step S563, if the transmission operation device 3 is changed to the Nrange, the process flow of the controller 100 goes to Steps S564 andS565. In Steps S564 and S565, the controller 100 turns off the starterdrive signal 100 a and turns off the pinion gear thrust signal 100 b.Then, the process flow goes to Step S566. In Step S566, the controller100 changes the current state to “during gear rotation stop and wait”,and the current task process is finished. Then, the process flow goes toStep S100 after a constant period of time.

If the current state is “during gear rotation stop and wait”, thecontroller 100 checks in Step S571 of FIG. 29 whether or not it ispredicted that the rotation of the ring gear 4 is stopped after passingof the pinion gear abutment delay time. If it is predicted that therotation of the ring gear 4 is stopped, the process flow goes to StepS572.

In Step S572, the controller 100 checks whether or not it is predictedthat the rotation of the pinion gear 5 is stopped after passing of thepinion gear abutment delay time. In this case, if it is not predictedthat the rotation of the pinion gear 5 is stopped (or if it is predictedthat the rotation is not stopped) after passing of the pinion gearabutment delay time, the controller 100 finishes the current taskprocess. Then, the process flow goes to Step S100 after a constantperiod of time. On the contrary, if it is predicted that the rotation ofthe pinion gear 5 is stopped after passing of the pinion gear abutmentdelay time, the process flow of the controller 100 goes to Step S573.

In Step S573, the controller 100 turns on the pinion gear thrust signal100 b, and the process flow goes to Step S574. In Step S574, thecontroller 100 changes the current state to “during gear rotation stopand wait and during pinion gear thrust” and finishes the current taskprocess. Then, the process flow goes to Step S100 after a constantperiod of time.

In addition, in Step S571, if it is not predicted that the rotation ofthe ring gear 4 is stopped (or if it is predicted that the rotation isnot stopped), the process flow of the controller 100 goes to Step S575.In Step S575, the controller 100 checks whether or not it is predictedthat the rotation of the pinion gear 5 is stopped after passing of thepinion gear abutment delay time. In this case, if it is predicted thatthe rotation of the pinion gear 5 is stopped, the controller 100finishes the current task process. Then, the process flow goes to StepS100 after a constant period of time. On the contrary, if it is notpredicted that the rotation of the pinion gear 5 is stopped (or if it ispredicted that the rotation is not stopped), the process flow of thecontroller 100 goes to Step S576.

In Step S576, the controller 100 checks whether or not the rotationspeed of the pinion gear 5 and the rotation speed of the ring gear 4 aresynchronized with each other after passing of the pinion gear abutmentdelay time. In this case, if the rotation speed of the pinion gear 5 andthe rotation speed of the ring gear 4 are not synchronized with eachother after passing of the pinion gear abutment delay time, thecontroller 100 finishes the current task process. Then, the process flowgoes to Step S100 after a constant period of time. On the contrary, ifthe rotation speed of the pinion gear 5 and the rotation speed of thering gear 4 are synchronized with each other after passing of the piniongear abutment delay time, the process flow of the controller 100 goes toStep S577.

In Step S577, the controller 100 turns on the pinion gear thrust signal100 b, and the process flow goes to Step S578. In Step S578, thecontroller 100 changes the current state to “during decrease in rotationspeed and during restart pinion gear thrust” and finishes the currenttask process. Then, the process flow goes to Step S100 after a constantperiod of time.

If the current state is “during gear rotation stop and wait and duringpinion gear thrust”, the controller 100 checks whether or not the piniongear abutment delay time has passed in Step S581 of FIG. 30. If thepinion gear abutment delay time has not passed, the current task processis finished, and the process flow goes to Step S100 after a constantperiod of time.

On the contrary, if the pinion gear abutment delay time has passed, theprocess flow of the controller 100 goes to Step S582. In Step S582, thecontroller 100 turns on the starter drive signal 100 a, and the processflow goes to Step S583. In Step S583, the controller 100 changes thecurrent state to “during cranking”, the current task process isfinished, and the process flow goes to Step S100 after a constant periodof time.

If the current state is “during decrease in rotation speed and duringrestart pinion gear thrust”, the controller 100 checks whether or notthe pinion gear abutment delay time has passed in Step S591 of FIG. 30.If the pinion gear abutment delay time has not passed, the current taskprocess is finished, and the process flow goes to Step S100 after aconstant period of time. On the contrary, if the pinion gear abutmentdelay time has passed, the process flow of the controller 100 goes toStep S592.

In Step S592, the controller 100 turns on the starter drive signal 100a, and the process flow goes to Step S593. In Step S593, the controller100 changes the current state to “during cranking”, the current taskprocess is finished, and the process flow goes to Step S100 after aconstant period of time. Other operations are the same as those ofEmbodiment 1.

Here, similarly to Embodiment 1, the pinion gear abutment delay time canbe determined in an experimental manner in advance. For instance, it ispossible to make settings so that the pinion gear thrust change quantitycan be detected and to define time necessary for the pinion gear thrustchange quantity to become constant after the pinion gear thrust signal100 b is input as the pinion gear abutment delay time ΔT. In addition,the pinion gear rotation speed can be estimated based on the pinion gearrotation speed when the starter motor drive is stopped and the lapsetime from the starter motor drive stop time point by referring to themap as illustrated in FIG. 23. In this way, the pinion gear rotationspeed N_(P) (ΔT) after the pinion gear abutment delay time ΔT has passedcan be estimated.

In addition, if the speed decrease amount of the ring gear rotationspeed when the engine is stopped is determined by experiment in advanceand is stored in the controller 100 in advance, a ring gear rotationspeed N_(E) (ΔT) after passing of the pinion gear abutment delay time ΔTcan be estimated from the current ring gear rotation speed. If thethrusting of the pinion gear 5 is started when the pinion gear rotationspeed N_(P) (ΔT) after passing of the pinion gear abutment delay time ΔTbecomes equal to the ring gear rotation speed N_(E) (ΔT) after passingof the pinion gear abutment delay time ΔT, the rotation speed can besynchronized between the pinion gear 5 and the ring gear 4 at the timingwhen the pinion gear 5 and the ring gear 4 abut against each other.

According to the automatic stop and restart device for an engine ofEmbodiment 6 described above, if the pinion gear 5 and the ring gear 4cannot engage with each other when the transmission operation isperformed in the engine restart process during the automatic enginestop, the controller 100 stops the engine restart process so as to stopdriving the starter motor 11 and separates the pinion gear 5 from thering gear 4. Then, if it is predicted that the pinion gear rotationspeed and the ring gear rotation speed are synchronized with each otherduring the period in which the pinion gear rotation speed and the ringgear rotation speed are decreasing, the controller 100 controls thepinion gear 5 to abut against and engage with the ring gear 4. Thus,time necessary for restarting the engine 1 can be further shortened.

What is claimed is:
 1. An automatic stop and restart device for anengine that is disposed in a start and transmission system of a vehiclewhich comprises: a transmission for changing gears to transmit power ofthe engine to driving wheels of the vehicle; a transmission operationdevice for receiving an external transmission operation to operate atransmission state of the transmission; a ring gear that is provided toa crank shaft of the engine, a starter motor for starting the engine; apinion gear that is capable of approaching and separating from the ringgear and is driven by the starter motor to rotate; a pinion gear thrustunit configured to thrust the pinion gear to the ring gear so that thepinion gear engages with the ring gear to crank the engine; and a ringgear rotation speed detection unit configured to detect a ring gearrotation speed, the automatic stop and restart device comprising acontroller which comprises a transmission state determination unitconfigured to determine whether the transmission is in a drive range orin a non-drive range, the controller performing an automatic stopprocess for the engine if a predetermined automatic engine stopcondition is satisfied, and a restart process for the engine bycontrolling drive of the starter motor and the pinion gear thrust unitif a predetermined restart condition is satisfied after thepredetermined automatic engine stop condition is satisfied, wherein thecontroller further comprises: a starter drive time measurement unitconfigured to measure starter motor drive time from a time point whenthe drive of the starter motor is started; a pinion gear rotation speedestimation unit configured to estimate a pinion gear rotation speedbased on the starter motor drive time; a first pinion gear thrust timingdetermination unit configured to drive the pinion gear thrust unit at atiming when a difference between the ring gear rotation speed and thepinion gear rotation speed, in a case where the transmission is in thedrive range, becomes a first predetermined value corresponding to aspeed decrease amount of the ring gear rotation speed in the case wherethe transmission is in the drive range; and a second pinion gear thrusttiming determination unit configured to drive the pinion gear thrustunit at a timing when a difference between the ring gear rotation speedand the pinion gear rotation speed, in a case where the transmission isin the non-drive range, becomes a second predetermined valuecorresponding to a speed decrease amount of the ring gear rotation speedin the case where the transmission is in the non-drive range.